Boss OC-2 Octave
Analog frequency-divider octave-down — Jack White, Tom Morello, every modern doom-rock riff.
We don't ship reference schematics until they've been hand-authored against authoritative sources (manufacturer service docs, ElectroSmash analyses, GEOFEX writeups) and reviewed in the simulator. Until then, the BOM, signal chain, controls and mod notes below are accurate, and you can still add this pedal to a project — it just won't include a circuit yet.
About
Pitch tracker (zero-crossing detector) drives a CMOS flip-flop chain (4013) to generate square waves one and two octaves below the input note. The square waves are low-pass filtered and mixed with the dry signal. Monophonic only — chords confuse the tracker — but on single notes it is rock-solid.
Signal chain preview
6 stagesQuick facts
- Released in 1982, discontinued in 2003, then revived as the OC-3 / OC-5; the original OC-2 remains the gold standard.
- Jack White's 'Seven Nation Army' bass-octave riff was an OC-2 set with -1 oct mixed under dry guitar.
- Two CD4013 dual flip-flops divide-by-two twice to produce -1 oct and -2 oct simultaneously.
Controls
- Direct (dry level)
- Oct 1 (-1 octave level)
- Oct 2 (-2 octave level)
Mod recipes Pro
3 mods- Tracking improvement
Smoother tracking on low/wound strings.
How: Tighten the tracking band-pass to a tighter 80-800 Hz window by reducing the high-pass cap from 0.1 µF to 0.047 µF and the low-pass cap from 0.022 µF to 0.0047 µF.
- Sub kill switch
Live toggle between -1 oct only and -1 + -2 oct.
How: Wire an SPDT switch in series with the Oct 2 pot's wiper to mute the -2 octave voice on demand.
- Mid-cut on dry
Carve a notch in the dry path to leave more room for the octave voices.
How: Insert a passive Wien-bridge notch (~700 Hz) between the dry buffer and the dry pot input.